Methods for positioning insulating members in magnetic core slots

ABSTRACT

Method is disclosed whereby permanent insulators made from known insulator material (e.g., polyethylene terephalate) are used in lieu of temporary fiber wedges, even though such wedges are not axially centered in core slots, without requiring the performance of manual labor in order to axially reposition the &#34;final&#34; wedges along the core slots. Previously positioned wedges are repositioned axially along core slots automatically and generally contemporaneously with the performance of some other necessary manufacturing process to avoid the expenditure of additional incremental time associated with such repositioning step. Equipment useable for other preselected manufacturing operations may be used in the automated practice of the method. In one specific exemplification, previously positioned wedges are repositioned along core slots during a previously known wire moving, wire shaping, or wedge setting operation. The equipment is provided with means for axially repositioning previously placed wedges relative to core slots while such apparatus is being used for also carrying out another preselected manufacturing operation.

BACKGROUND OF THE INVENTION

The present invention relates generally to apparatus and methods foraligning and placing insulators, such as insulators called wedges, alongslots of a magnetic core of a dynamoelectric machine.

Co-pending Kindig and Brown application Ser. No. 666,143, filed Mar. 11,1976 which subsequently issued as U.S. Pat. No. 4,026,009 on May 31,1977; and Bale U.S. Pat. No. 4,003,116 which issued Jan. 18, 1977, areboth directed to subject matter that is generally related to the subjectmatter of this application; and the entire disclosures of these twopatents are specifically incorporated herein by reference.

In the manufacture of dynamoelectric machine stator assemblies, diverseoperations are performed in order to place winding material and variousinsulating material members in and along axially extending slots of amagnetic core; and in order to properly orient, shape, or position theinsulating material members and winding material relative to the slots,bore, or end faces of the magnetic core.

One method used heretofore in the manufacture of stator assemblies hasinvolved placing insulating material, such as an epoxy coating or "slotliners" along the interior walls of slots that extend axially along amagnetic core and that open onto the bore of the core. Thereafter,winding turns of a first winding phase have been axially inserted alongthe slots, and fiber material wedges have temporarily been placed in theslots to hold the winding turns in the proper position therein. Then, ata later point in time, the temporary wedges have been removed and thrownaway; and insulators known as "phase", "window", or "H" insulators havebeen positioned over the winding material already in the slots; legs ofthe window insulation have been pressed back into the slots; and windingturns of a second winding phase have then been placed in the core slots.

In addition to all of the above, "final" slot closure insulators havebeen placed at the slot openings (between the slot accommodated windingconductors and bore) in order to prevent any winding conductors frommoving out of the core slots. The above referenced Bale patent clearlyreveals methods and apparatus that may be utilized for the purpose of"setting" the final slot closure insulators or "wedges", and togenerally simultaneously "shape" winding end turn envelopes.

On the other hand, the above referenced Kindig and Brown applicationfully discloses methods and apparatus that may be utilized when"separator" or "between phase" insulators are to be placed in core slotsafter winding conductors of a first winding phase have been placedtherein, but before winding conductors of a second winding phase areplaced in the same slots.

Persons of ordinary skill in the art will recognize that motors ofdifferent designs may be manufactured with winding arrangements suchthat some core slots will be shared by conductors of different phases,while other slots may be occupied by conductors of only one phase.Moreover, "shared slots" will usually include a phase separator wedge,and usually al of the slots will be provided with a slot closure wedge.Persons skilled in the art will also recognize that the wedges --whether of the phase separator or slot closure type -- may be placed inthe core slots substantially concurrently with the placement ofconductors therein, or after the conductors have been placed in theslots. Such persons will also recognize that such insulators are called"wedges" even though they are seldom, if ever, actually wedge-like inshape.

The above referenced Kindig and Brown application represents one mode ofcarrying out the latter approach just mentioned, while winding,injecting, and wedging equipment and processes of th type shown inArnold et al. U.S. Pat. No. 3,973,601 or injecting and wedging equipmenttypified by Hill U.S. Pat. No. 3,324,536 represent modes of carrying outthe former. For purposes of providing further background information,the entire disclosures of the just mentioned Arnold et al and Hillpatents are also incorporated herein by reference.

Regardless of the actual process or equipment used, it is desirable thatthe "final" slot closure or "final" phase separator wedges be generallycentered, lengthwise along the axially extending core slots, so that atleast generally similar amounts of wedge material extend out of theslots at each core face.

Some processes presently utilized for placing wedges -- particularlytemporary wedges -- result in "uneven" wedge placement, and if suchwedges were to be used permanently, it would be necessary for operatorsto manually position and center the wedges axially along the core slots.

In view of all of the foregoing, it should now be understood that itwould be desirable to provide new and improved methods that wouldestablish the desired proper positon of axially off center insulatorswithout the need to resort to extra manual labor steps.

Accordingly, an object of the present invention is to provide a new andimproved method of axially repositioning previously placed but axiallyoff center insulators (e.g., wedges) in the slots of magnetic cores.

It is a more specific object of the present invention to provide a newand improved method that involves axially repositioning previouslyplaced insulators in combination with (and generally contemporaneouslywith) the performance of at least one other manufacturing process stepwhereby there is no incremental amount of labor and time associated withrepositioning such insulators.

It is an even more specific object of the present invention to provideimproved methods of the type just mentioned which do not require largeamounts of capital investment or tooling expense in order to beeconomically put into use.

Yet another object of the present invention is to provide new andimproved apparatus that may be used to carry out the above mentionedmethods but which do not require large incremental capital investment ortooling expense prior to being useful for carrying out such methods.

SUMMARY OF THE INVENTION

In carrying out the above and other objects of the present invention inone preferred form thereof, I provide a new and improved method wherebytemporary and disposable fiber wedges may be dispensed with, and wherebypermanent insulators made from known insulator material (e.g.,polyethylene terephalate, commonly available under the tradename "MYLAR"from E.I. Du Pont de Nemours and Co.) are used in lieu of temporaryfiber wedges. Moreover, my preferred method permits first portions suchas direct substitution of "MYLAR" wedges for temporary fiber wedges,even though such wedges are not axially centered in core slots, withoutrequiring the performance of manual labor in order to axially repositionthe "final" wedges along the core slots.

In brief, I provide a new and improved method whereby previouslypositioned wedges are repositioned axially along core slotsautomatically generally contemporaneously with the performance of someother necessary manufacturing process. Thus, the previously positionedwedges are repositioned without the expenditure of additionalincremental time associated with such repositioning step. Moreover,multiple wedges are repositioned generally at the same time, thusmagnifying the time and labor savings associated with the use of mymethod. In addition, equipment already available and in use for otherpreselected manufacturing operations may be readily modified or adapted,at low cost, in order to permit the automated practice of my method.

In one specific exemplification of the invention, previously positionedwedges are repositioned along core slots during a previously known wiremoving, wire shaping, or wedge setting operation. In thisexemplification, previously known wire moving, wire shaping, or wedgesetting equipment is initially provided (or later retrofitted) withmeans for axially repositioning previously placed wedges relative tocore slots while such apparatus is being used for also carrying out thepreselected manufacturing operation for which such apparatus wasotherwise primarily designed.

The subject matter which I regard as my invention is particularlypointed out and distinctly claimed in the concluding portion of thisspecification. The invention itself, however, both as to itsorganization and mode of operation, together with further objects andadvantages thereof, may best be understood by reference to the followingdescription taken in connection with the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross-sectional view, in elevation, with parts removed andparts broken away, of a slotted magnetic core; and illustrates therelative position of winding conductors, a core slot, and a wedge, priorto practicing the present invention in one form thereof; and

Fig. 2 is a cross-sectional view in elevation, with parts broken awayand parts removed, of a previously known aparatus modified so as toembody the invention in one form, and which apparatus may be used topractice the invention in another form.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

With initial reference to FIG. 1, a stator assembly generally denoted bythe reference numeral 10 has been shown in order to explain in moredetail various aspects of the present invention. The assembly 10includes a magnetic core 11 which has a plurality of axially extendingslots 12 therein. Each such slot, enclosed at its radially outermostportion, communicates at an open end (or slot opening) with the axiallyor longitudinally extending bore 13 of the core. Disposed within atleast some of the slots are slot liner insulators 14, the side turnportions 16 of a winding, and a wedge 17.

It will be understood that wedge 17 may be a between phase insulator --assuming that side turn portions of another winding phase are to beadded to a slot on top of the winding material already in such slot. Onthe other hand, if ultimately the only conductors in a slot are to bethose behind a wedge 17, then the wedge 17 may be the final, or slotclosure wedge.

The insulator illustrated for exemplification as a wedge 17 in FIG. 1may be formed of any suitable material -- such as MYLAR material. Closeobservation of FIG. 1 will reveal that the wedge 17 is notlongitudinally or axially centered relative to slot 12. Thus, a greaterlength of wedge 17 at wedge end 18 protrudes beyond core face 19 ascompared to wedge end 21. In some cases in fact, wedge end 21 may belocated far down within a slot.

Heretofore, when temporary fiber wedges were used rather than wedges 17,the uncentered condition of the fiber wedges was immaterial, since theywere manually removed long prior to finishing the stator assembly 10. Inthe interest of reducing the cost associated with wasted fiber wedgematerial and manual removal of the same, the permanent insulatormaterial wedges 17 now may be used, but it will be understood that theaxially uncentered condition of the wedges 17 must be corrected.

It also will be understood that it would be extremely desirable toprovide a method of repositioning the previously positioned wedges 17during a subsequent or prospective preselected manufacturing operationwithout requiring the expenditure of additional time or labor because ofthe repositioning of the wedges 17. The importance of this becomes evenmore important when it is recalled that the stator assembly 10 actuallyincludes a plurality of wedges 17.

Attention now is directed to FIG. 1 and second portions of the windingshown as end turn portions 26, 27. It will be noted that the end turnenvelope at least partly established by end turn portions 26 projectsinto interfering relationship with an imaginary cylinder forming anextension of the bore 13. It usually is the case that the end turnenvelope containing end turn portions 26 will be at least partly shapedand moved at least to an intermediate position so as to betteraccommodate a second winding phase that is yet to be placed in slots ofthe core 11. Moreover, it is usual practice to at least lightly form theend turn envelope containing the end turns 27. Although various types ofequipment and diverse methods may be practiced to accomplish thisresult, one particular approach is described in the above-referencedBale U.S. Pat. No. 4,003,116.

In that patent, a wedge setting and winding end turn shaping apparatusis shown, among other things. For convenience, a preferred form ofpracticing the present invention, and a preferred mode of shaping thewinding, will now be described in conjuction with processes andapparatus similar to that shown and described in the referenced Balepatent.

In FIG. 2 I have shown apparatus 31 that may be used for purposessimilar to those described by Bale and yet also practice the presentinvention in one form thereof. Moreover, the apparatus 31 exemplifiesone form of the present invention.

More specifically, before using the apparatus 31, the push down yoke 32will be raised clear of the cap 33 of the apparatus. Then the statorassembly 10 of FIG. 1 is placed over the cap 33, oriented so that theslot openings of the core 11 are aligned with the blades 34, and a notshown ram cylinder, operative to drive the yoke rod 35, is energized inorder to move the stator assembly 10 until the ram cylinder bottoms out.At that time, the stator assembly 10 is in the position thereof as shownin FIG. 2. As the stator is moved downwardly in FIG. 2, the end turnenvelopes 36 and 37 are moved to the positions thereof as also shown inFIG. 2. After the push down yoke 32 stops moving, cam 38 is actuated.Actuation of cam 38 in the direction of arrow A causes blades 34 to"set" the wedges 17, and further shape (through interaction with shapingring 39) the end turn envelope 37 -- all of this being substantially asdescribed in more detail in the referenced Bale patent.

In carrying out the process just discussed, the previously positionedbut not "centered" wedges 17 will have been, according to my preferredmethod, repositioned axially relative to the core slots 12 and corefaces 19 and 22 as the stator assembly reached the final positionthereof shown in FIG. 2, and also prior to actuation of the cam 38.

The means for accomplishing this desirable repositioning result may takedifferent forms. However, in the embodiment shown in FIG. 2, such meansinclude a plurality of spring steel wedge pushers or stops 42. In theapparatus 31, the pushers 42 are carried by the bottom ring portion 43of a forming ring assembly 44. However, depending on the particular typeof apparatus used while practicing the invention, the wedge pushers or"stops" may be carried by any suitable part of such apparatus, as willbe understood.

When cores of different stack heights (i.e., different axial lengths)are to be operated on, the screws 46, 47 are loosened, these screwsnormally being tightened into machine base 48. Then a suitable number ofshims 49 are moved into or out of position under the bottom ring portion43 of the forming ring assembly 44. The screws 46, 47 are thenretightened. As will be understood, this will cause the spring membersto be raised or lowered to compensate for different core stack heights.

Although it is apparent from reading the above referenced Bale patent;it is now further noted, for purposes of description, that the blades 34(carried in slotted cage 51) return to an initial or "ready" positionunder the influence of garter springs 53, 54 when the cam 38 is raisedback to its initial position.

For purposes of emphasis, the method of the present invention will nowagain be described with reference to utilization of the apparatus 31.

The wedges 17 will have been previously prepositioned in the slots 12,an the stator assembly 10 will then be placed on the nose or cap 33 withthe extra wedge length directed downwardly as viewed in FIG. 2. At thistime, the wire trapped behind the wedges 17 will be forcing the wedgesagainst the press blades 34. As the stator assembly is forced down thearbor means that includes cage 51 and blades 34 by the action of pushdown yoke 32, the ends 18 of the wedges 17 will contact the upper orfree ends of the wedge stops (or pushers) 42. Then, as the core 11 ofthe stator assembly 10 moves to its final position (shown in FIG. 2),the relative position of the wedges and core is changed so that thewedges are repositioned and generally centered axially along the coreslots.

After movement of the push down yoke stops, the blades 34 expand intothe core slots to radially move and "set" the wedges 17, and movement ofthe blades 34 moves the flexible spring steel wedge pushers 42 outwardlyaway from the wedges. Thus, the pushers 42 will then no longer affectthe wedge position.

While preferred embodiments of the present invention have been describedherein in relation to specific known processes and apparatus, it will beunderstood that the invention itself is not so limited; and changes andmodifications may be made without departing from the invention. It istherefore intended in the appended claims to cover all such changes andmodifications that fall within the spirit and scope of the inventiondefined by such claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:
 1. A method of performing a preselected manufacturingoperation on a stator assembly and also axially repositioning aplurality of previously placed axially extending insulators carried inslots of a magnetic core along with side turn portions of at least onewinding, said method comprising: performing the preselectedmanufacturing operation and, while performing such operation, alsoaxially repositioning the plurality of previously positioned insulatorsalong slots of the magnetic core.
 2. The method of claim 1 wherein thepreselected operation includes moving a winding end turn enveloperelative to the bore of the core and wherein the previously positionedinsulators are axially repositioned within the period of time expendedin performance of the preselected operation.
 3. A method of axiallypositioning insulators previously placed in axially extending slots of amagnetic core that comprises part of a stator assembly, said methodcomprising repositioning the insulators generally contemporaneously withthe performance of at least one other preselected manufacturingoperation involving the stator assembly, whereby the previously placedinsulators are axially repositioned along the slots within the same timeperiod as other manufacturing procedures.
 4. The method of claim 3wherein the previously placed insulators are repositioned by apparatuswhile the same apparatus is operational in conjunction with theperformance of said other preselected manufacturing operation.
 5. Themethod of claim 4 wherein the stator assembly includes windingconductors having first portions disposed in slots of the core, andsecond portions extending out of the slots at each end thereof andforming end turn envelopes; and wherein said other preselectedmanufacturing operation includes moving at least some of the secondportions of the conductors.
 6. The method of claim 4 wherein said otherpreselected manufacturing operation comprises placing the core on anarbor, moving the core and previously placed insulators axially alongthe arbor, and relatively moving the previously placed insulatorsradially relative to the core.
 7. The method of claim 6 wherein therepositioning of the insulators comprises arresting axial movement ofthe previously placed insulators while continuing to move the corerelative to the arbor.
 8. The method of claim 6 wherein said otherpreselected manufacturing operation includes moving at least some of theend turn portions of winding coils supported in the core slots; andmoving at least some of the previously positioned insulators radially inthe core slots after such insulators have been axially repositionedalong the core slots.